Active: Akali moves through the shadows to quickly deal magic damage to the target and appear next to it. Akali gains an Essence of Shadow charge once every few seconds up to a total of 3, affected by cooldown reduction. The time to gain a charge doesnt count when at maximum charges. Additionally, Akali gains an Essence of Shadow for a kill or an assist.
Cost: 1 Essence of Shadow
Range: 800
Cooldown: 2/1.5/1 seconds
Essence of Shadow Recharge Time: 35 / 25 / 15 seconds
Magic Damage: 100/175/250 (+0.5 per ability power)

+400 Health
+100 Ability Power
UNIQUE Passive: Damaging spells and abilities apply a Movement Speed reduction to enemies based on the spell type:
Single Target: 40% reduction for 1.5 seconds.
Area of Effect: 40% reduction for 1 seconds.
Damage over Time or Multi-hit: 20% reduction for 1 seconds.
Summoned Minions: 20% reduction for 1 seconds.
(If a spell fits in more than one category, it uses the weakest slow value.)

Endgame items

Zhonya's Hourglass

+100 Ability Power
+45 Armor
UNIQUE Active - Stasis: Champion becomes invulnerable and untargetable for 2.5 seconds, but is unable to move, attack, cast spells, or use items during this time (90 second cooldown).

which items should you buy

you have to remember akali have to deal dmg and she doesn't need too much HP and resists. never buy torment's cause it's don't deal any dmg with akali. One of the worst fault's on akali Will of the ancients that's give you AP and spell wamp but it's not worth that, if you need more spell wamp just finish gunblade and never buy other items with spell wamp.

Quintessence

runes

you should take flat AD marks because it gaves you more spell wamp and really help with farming on lane, Flat armor seals should disable bit dmg from basic atacks (that's important if you play versus ranged champion)